feat: Add @mention support to comments (#5001)

* Refactor, remove confusing 'packages' language

* Basic notifications when mentioned in comment

* fix: Incorrect trimming of comments

* test

server/models/helpers/DocumentHelper.test.ts

@@ -1,7 +1,38 @@
 import Revision from "@server/models/Revision";
+import { buildDocument } from "@server/test/factories";
 import DocumentHelper from "./DocumentHelper";
 
 describe("DocumentHelper", () => {
+  describe("parseMentions", () => {
+    it("should not parse normal links as mentions", async () => {
+      const document = await buildDocument({
+        text: `# Header
+    
+[link not mention](http://google.com)`,
+      });
+      const result = DocumentHelper.parseMentions(document);
+      expect(result.length).toBe(0);
+    });
+
+    it("should return an array of mentions", async () => {
+      const document = await buildDocument({
+        text: `# Header
+    
+@[Alan Kay](mention://2767ba0e-ac5c-4533-b9cf-4f5fc456600e/user/34095ac1-c808-45c0-8c6e-6c554497de64) :wink:
+
+More text
+
+@[Bret Victor](mention://34095ac1-c808-45c0-8c6e-6c554497de64/user/2767ba0e-ac5c-4533-b9cf-4f5fc456600e) :fire:`,
+      });
+      const result = DocumentHelper.parseMentions(document);
+      expect(result.length).toBe(2);
+      expect(result[0].id).toBe("2767ba0e-ac5c-4533-b9cf-4f5fc456600e");
+      expect(result[1].id).toBe("34095ac1-c808-45c0-8c6e-6c554497de64");
+      expect(result[0].modelId).toBe("34095ac1-c808-45c0-8c6e-6c554497de64");
+      expect(result[1].modelId).toBe("2767ba0e-ac5c-4533-b9cf-4f5fc456600e");
+    });
+  });
+
   describe("toEmailDiff", () => {
     it("should render a compact diff", async () => {
       const before = new Revision({